1. Field of the Invention
This invention relates to a disk drive apparatus which drives a disk-like recording medium, particularly to a head retract mechanism which retracts a read and/or write head from the recording medium at non-operating time.
2. Description of Related Art
FIG. 1 is a perspective view showing an example of a conventional disk driving apparatus having a head retract mechanism disclosed in PCT Publication No. WO 89/08313, filing date Feb. 27, 1989. FIG. 2 is a perspective view showing a detailed structure of the head retract mechanism. In the figures, reference numeral 3 is a read and/or write head for reading and/or writing a magnetic disk 1 which is rotatably driven by a spindle motor 2, the read and/or write head 3 comprising of a slider 4 and a coil 41 fixed at one side of the slider 4. The slider 4 is attached to the tip of a tapered flat spring 5 with a gimbal spring, being supported by the flat spring 5 so that it is energized towards the magnetic disk 1. In the middle of the spring 5, a cam follower 51 is set, which engages with a latch groove 91 of a ramp-type cam 9 to be described later is set. The base tip of the flat spring 5 is attached to an actuator 6 which rotates around a pivot shaft 61. The actuator 6 is in the form of an arm, on the tip of which is attached flat spring 5. The actuator 6 moves the read and/or write head 3 on the magnetic disk 1 to the loading direction shown by an arrow 12 and to the retracting direction (unloading direction) shown by an arrow 13. The spindle motor 2, actuator 6 and the cam 9 are attached to a base 10. The cam 9 is attached to base 10 along the radial direction of the magnetic disk 1 so that it engages with the cam follower 51 of the flat spring 5. The cam 9 has a section which surrounds the outer edge of the magnetic disk 1, and has a ramp and a latch groove 91 formed on the upper and lower sides of the cam 9 for latching the cam follower 51.
Next, explanation will be given on loading/retracting operation of a conventional disk driving apparatus constructed in such a way. FIG. 3 is an enlarged sectional view explaining the conventional loading/retracting operation.
In FIG. 3, when the power source is turned off, the cam follower 51 coupled with the spring 5 of the read and/or write head 3 rides on the cam 9 and is held at the latch groove 91, and the slider 4 detaches from the magnetic disk 1, but when the power source is turned on, the spindle motor 2 is driven to rotate the magnetic disk 1 supported by the spindle motor 2. Next, when the actuator 6 is driven to the loading direction 12, the cam follower 51 coupled with the spring 5 of the read and/or write head 3 rides across the latch groove 91 further to slide down the cam 9, the slider 4 being loaded on the magnetic disk 1. When the power source is turned off again, by using electric power stored in a capacitor or the like not shown in the figure, for example, the magnetic head 3 is driven to the retracting (unloading) direction 13 by the actuator 6, the cam follower 51 connected with the spring 5 being stranded on the cam 9 and the slider 4 being hung down in the air. It stops when it reaches the latch groove 91. The operation of the slider 4 at this time is shown by a motion line shown by an arrow 15.
FIG. 4 is a perspective view showing a construction of a disk driving apparatus of a conventional contact start stop method (CSS) which does not load/unload the read and/or write head 3 but starts/stops the spindle motor 2 in the state of remaining contacted with the magnetic disk 1. In the CSS method, the retract mechanism is not provided, and the read and/or write head 3 is made to be static at a time of non operation on a shipping zone provided at the innermost circumference of the magnetic disk 1. At an activation time of the magnetic disk apparatus of the CSS method, the spindle motor 2 is rotated with the slider 4 of the read and/or write head 3 being made to be static on the magnetic disk 1. Generally, the slider 4 is made to be static at the shipping zone to the inner circumference side of the magnetic disk 1. Although, at the beginning, the slider 4 rubs the magnetic disk 1, when the number of rotations exceeds the prescribed number, the slider 4 begins to rise on the magnetic disk 1 due to the air bearing effect. When the spindle motor 2 rotates regularly, it rises above the disk about 0.2 .mu.m. In addition, at a stopping time of the magnetic disk apparatus, the slider 4 begins to touch the magnetic disk 1 when the number of rotations of the spindle motor 2 reduces from the regular number to a certain number, the slider 4 continuing to be rubbed with the magnetic disk 1 until the spindle motor 2 is stopped. Accordingly, a device which positively stops the spindle motor 2 is being developed.
In a conventional magnetic disk apparatus having a retract mechanism, when the power source is turned off, as it is in the retract state and the slider of the magnetic head floats in the air, there has been a problem that, in the case where vibration and shock are added from the exterior, stress is added to the flexible and thin gimbal spring of coupling part of the slider and the spring and the read and/or write head is easy to be destroyed.
On the other hand, the CSS method has a problem that, the less the height the slider rises from the magnetic disk becomes, the less the number it can CSS, that is, the expected life span, becomes. The more the recording density becomes high, the less the height needs to be. Accordingly, the distance in which the slider rubs the disk is elongated that much to enlarge aforesaid problem.
In addition, as the slider touches directly to the disk, there has been a limit upon withstanding vibration and shock at the time of non operation. Moreover in the case where the slider does not rise above the disk for some reason, there has been a danger that all of the data having been recorded on the magnetic disk may be destroyed. Furthermore, when the contact resistance of the slider and the disk increases resulting from the fact that the number of disks as being the recording medium increases due to high capacity, the spindle motor having big activating torque that much has been required. In addition, in this method, as it is not possible to rotate the spindle motor in the opposite direction of rotation to the regular one at the time of activation, an angle position detecting means accurate to a certain extent has been required in the driving circuit of the spindle motor. Moreover, means for reducing coast time of the spindle motor at the stopping time has been also required.